FAMILY FUN - A carousel and wooden shops are part of the Christmas market at the Natural History Museum skating rink. CNS Photo by Joan Scobey.

SEASONAL SPIRIT - At The Grove, even the statuary is dressed for Christmas. CNS Photo by Joan Scobey.

One important thing to know is that it's two days long. There's Dec. 25, and cobbled to it is Dec. 26, Boxing Day, another official holiday, making two days when much of the country is closed for business and celebrating at home. This tends to cramp a visitor's style in London, but turns a country stay into leisurely merrymaking. So here's my suggestion: Split your holiday into town and country; London in the run-up for its only-this-time-of-year special events, then to the country where candles and mince pies come into their own.

If you're wondering what Boxing Day is, historically, it was when employers gave presents, perhaps in boxes, to their workers, a day after exchanging them with their equals.

For your two home bases, go family friendly. In London, one favorite is the apartment part of Athenaeum Hotel & Apartments, which combines hotel services with one- and two-bedroom town house flats; it's like having your own London digs with hotel services. In the country, it's The Grove, an 18th century estate in nearby Hertfordshire, but more of that later.

By and large, London streets aren't filled with holiday sights or sounds. It's a restrained display, short on sidewalk Santas. But just because London isn't blasting a big red and white Ho, Ho, Ho on every corner, don't think there isn't a joyous yuletide going on.

Take the city's most famous Christmas tree, the one at Trafalgar Square. Austere rather than gaudy, it is decorated in traditional Norwegian style with spare vertical lines of round, not twinkling, bulbs. Donated annually since 1947, a plaque in front of it reads: "This tree is given by the City of Oslo as a token of Norwegian gratitude to the people of London for their assistance during the years 1940-45." It is lit from noon to midnight, with carol singing around the tree most evenings.

For a more festive tree, and one of London's favorite winter activities, stop by Somerset House on the Strand where the spacious courtyard becomes a gorgeous ice skating rink, framed between a towering tree and the elegant lighted dome of Somerset House, an 18th century neoclassical beauty. It's a great scene with parents holding up wobbly kids, a dad whizzing by gripping a child between his knees and giggling skaters falling down.

London has dozens of skating rinks, but my other favorite is at the Natural History Museum. There a German-style Christmas market of wooden huts overflows with holiday trinkets and toys, kids ride a carrousel and families picnic at wooden tables on hot sausage cobs of wild boar and apple, hot chestnuts and mulled wine.

The city's best-known lights in Regent Street often feature comic figures. Last year, for instance, sailing over the shoppers were Spike and Whitey from "Flushed Away," a popular animated potty-humor film.

With music the holiday language, opportunities abound to hear Handel's "Messiah," Christmas music and carols. Watch for the offerings at St Martin-in-the-Fields, Royal Albert Hall and Royal Festival Hall. More enchanting even than "The Nutcracker" at the Royal Opera House at Covent Garden are sparkly-eyed, would-be ballerinas out with their dads, twirling in the aisles in gorgeous frilly dresses and gold slippers.

One of the great British theatrical traditions that springs to life during the holidays is panto, short for pantomime. But don't mistake it for silent acting; it's more like raucous English music hall. Based on traditional children's stories, it has a set of conventions all its own: the young hero is played by a woman and the bawdy comedienne by a man, double entendres, groaner puns, slapstick pratfalls and, most important, riotous audience participation, with kids (and their parents) screaming, "Look behind you!" "No, he's over there!"

Two years ago, panto became practically mainstream when Shakespearean heavyweight Sir Ian McKellen hammed it up as Widow Twankey in "Aladdin" at the Old Vic and brought the house down. This year's Old Vic panto is "Cinderella" - keep an eye out for any surprises Kevin Spacey, its artistic director, has up his sleeve.

Get out to The Grove, the Athenaeum's country cousin in Hertfordshire, in time for Christmas Eve caroling and mulled wine festivities. It's barely more than half an hour drive, so close it's often called London's country hotel.

Drive through the estate's rolling parkland to the 18th century red brick Georgian mansion, once the home of Hon Thomas Villiers, British Ambassador to France and 1st Earl of Clarendon, and now seamlessly expanded to a 227-room country resort.

Inside there's no mistaking it's holiday time: Clerks wear Santa hats and headbands with funny bobbling balls, Christmas trees brighten the lounges, practically every table has a jar of candies or cookies, and Father Xmas (Mother, too) roams the hotel.

If London is a holiday whirl, The Grove is deliciously indolent. Major decisions revolve around which of its three restaurants to book: Colette's for foie gras confit with fig compote, chestnut-crusted venison and other sophisticated French fare? The rustic Stables for fish and chips, wood-burning-oven pizzas and treacle tart? Or The Glasshouse with its all-day groaning board of British, Mediterranean and Asian dishes?

Between meals it's whether to cycle, jog or just walk the trails through the estate's 300 acres, past the Grand Union Canal, wetlands, lakes and award-winning formal gardens. Perhaps a round of golf? A swim in the indoor mosaic-lined pool? Nah, let's sit by the fire in the library with mulled wine and mince pies after a languorous massage in the Sequoia Spa.

For kids, there are carols on Christmas Eve, stockings hanging on their doors on Christmas morning, making presents in Santa's workshop and receiving them in Santa's grotto. At lunchtime on Christmas Day a chimney sweep look-alike does magic tricks at the table, and a roustabout blows balloons into crowns, swans, swords and other wondrous objects. And on Boxing Day there's a magic show by the elves. Cries of wonder, yelps of delight, even whines of fatigue are the perfect holiday soundtrack.

There's nothing wrong with the new 201-room, contemporary-style wing, but for character - what The Grove calls Groovy Grand - opt for one of the 26 rooms in the original mansion. Of the three styles of decor - classic, contemporary and decadent - I was lucky enough to draw the last: steel-rod-in-Plexiglas four poster swathed in brown netting and crowned with four black ostrich feathers. It was atmospheric and a little dark, but isn't that the point?

Oh, the other thing to know about this holiday is that the Brits say "Happy Christmas," not Merry.

The Grove, Chandler's Cross, Hertfordshire, WD3 4TG, phone 011-44-1923-807807, www.thegrove.co.uk. Two hundred twenty seven rooms and suites, all with 42-inch, wall-mounted plasma screens, DVD-CD and high-speed Internet access. There's a walled garden with two tennis courts and croquet lawn, and a championship 18-hole golf course. Sequoia Spa has a wide-ranging menu of Espa spa treatments, 13 treatment rooms and its own black mosaic-tiled, 72-foot indoor pool. Anouska's Kids' Club is a certified day care program masquerading as a most-fun house in a separate complex, with its own indoor pool and outdoor adventure playground. Three-night Christmas package for two, including all meals and reception, from £700. Check the Web site for other packages.